This invention relates to apparatus for indicating the amount of tape wound upon a reel, such as a supply reel or a take-up reel in a two-reel cartridge and, more particularly, to such apparatus wherein this indication is provided after the reel is rotated one or more times while tape is transported therefrom, such as during a loading operation wherein the transported tape is withdrawn from the cartridge and into a processing device.
In tape recording/reproducing apparatus, such as in audio tape recorders, video tape recorders (VTR's), and the like, an indicator usually is provided to indicate either the amount of tape which has been transported from a supply reel to a take-up reel, or the amount of tape which remains on the supply reel during, for example, recording or reproducing operations. Such indicators typically are digital counters which provide a so-called tape count that is incremented or decremented by the forward or reverse movement, respectively, of tape through the recorder/reproducer. If a fresh tape, that is, a tape which is completely wound upon the supply reel, is loaded into the device, then the tape counter provides a reasonably close approximation of the amount of tape which has been consumed (i.e., the amount of tape which has been transported from the supply reel) or the amount of tape which remains for further recording or reproduction.
However, if a tape cartridge that has been partially used, that is, some amount of tape already has been used for recording or reproduction, is loaded into the device, the tape counter cannot indicate how much tape remains on the supply reel or how much tape already has been wound upon the take-up reel. To obtain such an indication from the tape counter requires that the present position of the tape be noted, and then the tape be rewound completely in order to set the tape counter to an initial, zero count, and then the tape must be transported back to its last position so that the amount of tape which had been used can be accounted for by the tape counter. It is appreciated that this is a time-consuming and annoying task. Nevertheless, it often is necessary for a user to be apprised of the amount of tape which remains in preparation for a recording operation, for example, so that the user can ascertain if there is a sufficient amount of tape available for his purpose.